1. Field of the Invention
The present invention relates generally to stacker-reclaimer apparatus for handling bulk material at a storage site.
The present invention further relates to a method for handling bulk material at a storage site.
2. Description of the Related Art
Stacker-reclaimer apparatus are utilized for stacking and reclaiming bulk material, such as wood chips. Typically, such stacker-reclaimer devices employ a central tower to which a stacker boom and a reclaimer boom are mounted. The stacker boom deposits bulk material on the pile. The reclaimer boom is equipped with a conveyor for conveying the reclaimed material towards the central tower. From there, the material is discharged into a discharge or reclaim conveyor. The stacker boom and the reclaimer boom may be rotated about the vertical axis of the central tower.
One example for a known stacker reclaimer device is disclosed in U.S. Pat. No. 8,177,053. In this prior art, the reclaimer assembly has a stationary axis of rotation during reclaiming of material. For this purpose, the outer end of the reclaimer assembly is supported on a rail guide. A harrow extends upwardly and angularly away from the reclaimer assembly in contact with the face of the pile of bulk material, thereby enabling pushing or raking of material into a transfer chute in a pit below the central tower. The reclaimed material is then passed to an enclosed tubular air cushion conveyor outfeed.
It is a disadvantage of this device that a rail guide is required to support the reclaimer assembly during rotation about the vertical axis. Furthermore, supporting the central tower is intricate in this construction.
Another prior art stacker-reclaimer apparatus is shown in U.S. Pat. No. 7,226,011 B2. In this prior art, the reclaimer apparatus is made of a pivotal reclaim conveyor assembly mounted to a main platform. The pivotal reclaim conveyor assembly is made of at least one continuous chain loop around a head sprocket and around a tail sprocket, both sprockets mounted rotatably in bearings at opposite ends of the pivotal reclaim conveyor assembly. The pivotal reclaim conveyor assembly functions by transporting bulk material from the pile in a plurality of rakes, when the plurality of rakes is on the bottom of the continuous loop. The plurality of rakes along the bottom of the pivotal reclaim conveyor assembly will move bulk material during operation if the pivotal reclaim conveyor assembly is lowered an appropriate distance by means of a hoist, hoist cable parts and a boom yoke down into the pile of bulk material and will continue to move bulk material if the pivotal reclaim conveyor assembly is rotated or slewed in the horizontal plane by means of slewing drive and slewing drive chain.
A drawback of this construction is that the rakes on the pivotal reclaim conveyor are subject to significant wear and tear. Accordingly, maintenance costs are high. Furthermore, the pivotal reclaim conveyor carrying the rakes requires a massive body portion for mounting on the central tower. This puts a limit to the area of the storage site available for storing bulk material. Also, the known construction does not enable the reclaiming of bulk material according to the “first-in-first-out” principle. Another drawback of this prior art solution is that a shaping of the pile of bulk material is required during operation.
It is an object of the invention to alleviate at least some of the problems associated with the prior art stacker-reclaimer apparatus.